This Core will maintain existing lines of transgenic (and other) mice and will provide animals of various ages (from embryos to aged adults) to projects within this program. The Core is organized with two dominant Specific Aims: Maintaining transgenic mice relevant to the study of presenilin biology and Alzheimer disease and to provide animals of various ages (from embryos to aged adults) to investigators. Organizing and coordinating animal requirements across the individual projects to make maximal and efficient usage of this important, expensive and limited resource. Animals to be covered in this Core include locally generated mice expressing mutant (M146L) or wild type forms of human PS1, wild type human APLP2, as well as animals generated in other laboratories. The later include several transgenic models in which A_ deposition occurs as the consequence of a mutant form of APP (with or without mutant forms of PS1). These lines include the Tg2576 line of mice [over-expression of APP-Sw alone], the APPswe/PS1dE9 line of mice [with over-expression of both APPSw and the exon 9 deleted form of PS1] and the J20 line of mice [over-expression of APP-Sw,Ind ]. The Core will also work with investigators of the Program Project to develop new lines of mice relevant to their projects should these become relevant. Thus a potential third Specific Aim of the Core is to: Participate, in collaboration with the relevant investigator(s), in developing and characterizing and utilizing new mouse models. By consolidation of efforts involving animals, the Program Project seeks efficient use of animal resources, through the coordination of requests from different investigators and sharing of the animals when possible. This will help to keep animal numbers and costs are kept as low as possible while ensuring that, within the limits of colony space, the needs of investigators in all projects are met. Animals from this Core are also made available, as possible, to investigators outside of the Program Project.